Feeding mechanism for sewing machines



Dec. 30, 1958 Filed April 4, 1957 E. WRASE FEEDING MECHANISM FOR SEWING MACHINES 6 Sheets-Sheet l Dec; 30, 1958 E. wRAsE FEEDING MECHANISM FOR SEWING MACHINES 6 Sheets-Sheet 2 Filed Aprif 4, 1957 Dec. 30, 1958 E. wRAsE FEEDING MEcHANIsM Foa SEWING MACHINES 6 Sheets-Sheet 4 Filed April 4, 1957 Dec. 30, 1958 E. wRAsE "2,866,425

FEEDING MECHANISM FOR SEWING MACHINES Filed April 4, 1957 6 Sheets-Sheet 5 WK/M Dec. 30, 1958 E. wRAsE 2,866,426

FEEDING MECHANISM FOR SEWING MACHINES Filed April 4, 1957 6 Sheetsi-Sheet 6 /N VENT OP Erich IMP/15E ilnited States Patent Office 2,866,426 Patented Dec. 30, 1958 2,866,426 FEEDING MECHANISM FOR SEWING MACHINES Erich Wrase, Kaiserslautern, Pfalz, Germany, assignor to G. M. Pfaff A. G., Kaiserslautern, Pfalz, Germany Application April 4, 1957, Serial No. 650,775 Claims priority, application Germany April 17, 1956 l Claims. (Cl. i12-214) The invention relates to a material advancing or feeding mechanism for sewing machines of the type having a feeding wheel which is provided under the base plate in a vertically adjustable swinging frame.

it is known to have the feeding wheel of a sewing machine rotate with different feeding speeds. For this purpose there have been provided, among other arrangements, change gears and shifting transmissions. The number of the feeding speeds which can be attained with the known arrangements of this type is limited for structural reasons, because the transmissions are built into the swinging frame of the feeding wheel. In the shifting transmissions the feeding speed depends on the number of pairs of wheels which mesh with one another, and with the changing gears it depends on the number of pairs of change wheels which are available. As a result of the arrangement of the transmissions in the vertically adjustable swinging frame of the feeding wheel, it is necessary to swing up the upper part of the sewing machine in order to select a different feeding speed. Moreover, it cannot be determined from the outside for which feeding speed the mechanism is set at any particular time.

It is an object of the invention to provide a simple and reliable increase in the numbers of turns of the feeding wheel Without requiring the upper part of the sewing machine to be raised for the purpose of setting the suitable feeding speedrequired at any particular time.

It is a further object of the invention to provide an arrangement in which the feeding speed can be readily determined at any time.

in accordance with the invention these objects are achieved in that for changing the speed of the feeding wheel two shifting transmissions are arranged in alignment with each other, which are mounted upon hollow shafts and which are selectively shiftable by means of switch bars guided therein for operating draw keys from a common stitch setting device provided above the base plate.

It is suitable for this purpose to arrange the two shifting transmissions in a common transmission case below the base plate. Preferably, the shifting levers of the two shifting transmissions are secured to concentrically arranged shifting shafts in the standard of the machine which are in operative engagement with the shifting bars of the draw keys by way of the transfer levers. In this arrangement one of the two shifting levers is provided with an indicator scale which cooperates with a scale secured on the machine housing and which is also nrovided with markings for the other of the two shifting levers.

Further objects and details of the invention will appear from the following specification of an embodiment of the new feeding mechanism illustrated in the attached drawings where Fig. 1 is a front view of a sewing machine partially in cross-section provided with the new feeding mechanism;

Fig. 2 is a view, partly cut olf, showing the sewing madriving mechanism of the machine drawn chine from the bottom with the transmission cover removed;

Fig. 3 is a section taken along lines III- III in Fig. 2 drawn to an enlarged scale;

Fig. 4 is an end view of the components of the lower to an enlarged scale;

Fig. 5 is a` section taken through the transmission box along line V-V in Fig. 2 drawn to an enlarged scale;

Fig. 6 is a partial View of the machine taken along line Vl-VI in Fig. l drawn to an enlarged scale;

Fig. 7 is a section taken along line VII- VII of Fig. 6; and

Fig. 8 is a perspective view of the stitch setting device with parts cut away, drawn to an enlarged scale. g

The base plate 1 of the sewing machine supports the standard 2 on which is formed the horizontal arm 3 which ends in the machine head 4. The arm shaft 8 is journalled in the arm 3 in bearing sleeves 5, 6 and 7, and it carries the balance wheel 9 at one end and at the other end the crank lil, which is in operative engagement with the needle bar 12 by way of the needle bar member 11. The needle bar 12 is mounted in the needle bar oscillator 14 which pivots about the bolt 13 and carries at its lower end the needle 15. The needle bar oscillator 14 is guided by the slide member 16 secured inside the head 4.

The swinging of the needle bar oscillator 14 is. effected by the crank 17 which is secured upon the rocking shaft 18 which is journalled in the arm 3. A forked lever 19 which is mounted on the rocking shaft is in operative engagement with the cam 20 which is adjustably mounted upon the arm shaft 8. The adjustment of the eccentricity of the cam 20 is effected manually upon engagement of the spring biased latch 22 provided in the cover 21 of the arm with the detent bore 23 of the adjustment member 24 by rotating the arm shaft 8. The components of the lower stitch forming mechanism Vare driven from the arm shaft 8 of the machine. A bevel gear 2S is secured to the shaft 8 which meshes with a bevel gear 26 mounted at the upper end of a vertical shaft 29 journalled in cast bearing members 27 and 28 provided in the standard 2. The vertical shaft 29 which reaches below the base plate l in a transmission box formed thereon is also journalled at the lower end by means of a bearing sleeve 33 in a socket 3l provided in a cover 32. The cover 32 is secured to the transmission box 30 by means of screws 34 which engage thread bores 35 (Fig. 2) of the box 30. At the lower end of the vertical shaft 29 a bevel gear 36 is provided which meshes with the bevel gear 38v secured to the shaft 37 for the looper. The looper shaft 37 is journalled in unitary conformations 39, 40 of the base plate 1 as well as in the Wall of the transmission box 30 by means of sleeves 41, 42 and 43, and is secured by means of set collars 4d and 45. It is in operative engagement with the looper shaft 49 which supports the looper 48 (Fig. 1) by means of the oair of bevel gears 46 and 47. Shaft 49 is journalled in the support 50 (Fig. 2) which is secured upon base plate 1 by means of screws 51.

The bar for the stepper 52 (Fig. 1) which is biased by a spring is provided in the head 4 of the machine and is provided at the lower end with the carrier 53 for the roller foot 54, which is journalled thereon. The feeding wheel 57 which is secured below the base plate 1 upon a shaft 55 (Fig. 2) by means of a screw 56 cooperates with the roller foot 54.

The feeding wheel 57 is driven by the vertical shaft 29 (Fig. 3). For this purpose a worm gear 58 is mounted on the vertical shaft and meshes with a worm wheel 59 screw 61 (Fig. 5). The shaft 60 is journalled in sleeves wheel 59 are secured against axial movement by means of a locking collar 71.

Toothed gears 64-67 mesh with toothed gears 72, 73, 74 and 75 of the other set of gears of the shifting transmission 68, which are rotatably mounted upon a hollow shaft 77 separated thereon by spacing rings 76 and are secured against axial displacement by means of locking collars 78 and 79.

The toothed gears i2-75 are each provided with six grooves80 equally distributed around the peripheries of the bores thereof for selective engagement by adraw key 81 which is rotatably secured in a cylindrical member 82 of a switching bar 83 guided longitudinally in the hollow shaft 77. The cylindrical member 82 is provided for this purpose with a slot 84 which receives the draw key 81 which is secured therein by means of a pin 85. The draw key 81 is biased by a spring 86 which presses it into one ofthe grooves of a selected toothed gear for coupling the hollow shaft 77 with the toothed gear. The spring 86 is wound around the pin 85 and rests with one end against the draw key 81 which is provided with a slot 87 and at its other end it extends into a bore 88 of the cylindrical member 82 of shift bar 83.

The hollow shaft 77 is journalled in sleeves 89 and 90 which are securely fastened in the walls of the transmission case 30. Toothed gears 91, 92, 93 and 94 are also secured upon hollow shaft 77 by -means of a key 96 forming part of one of the sets of gears of a shiftable transmission 95. A set collar 97 secures the toothed gears 91-94, and an additional set collar 98 secures also the hollow shaft 77 against axial displacement.

The toothed gears 99, 100, 101 and 102 of the other set of gears of the transmission mesh with the toothed gears 91-94, and are rotatably journalled on a hollow shaft 104 separated from one another by means of spacing rings 103. In a manner similar to the toothed gears 72-75, toothed gears 99-102 are also provided with grooves 105 which are equally distributed around the circumference of their bores for selective engagement by a draw key 106 which is mounted for pivotal movement in a cylindrical `member 107 or' a shifting bar 108 movable longitudinally in a hollow shaft 104. The draw key 106 is arranged in a similar manner as the draw key 81 for pivotal movement about a pin 110 in a slot 109 of the cylindrical member 107 and is biased by means of a spring 111 in one of the grooves 105 of one of the selected toothed gears 99-102 for the purpose of coupling the hollow shaft 104 with this toothed gear.

The hollow shafts 104 and 60 are mounted coaxially and are of equal diameter. The sleeve 62 forms at the same time also a bearing vfor the hollow shaft 104, which is also journalled in a sleeve 112 secured in the transmission box 30 and in a bearing lug 113 (Fig. 2) of the base plate 1. The hollow shaft 104 is secured against axial displacement by set collars 114 and 115.

The support 50 is provided with a bore 116 of larger diameter than the shaft 104 to insure on the one hand for free passage of the shaft and, on the other hand, to avoid interfering with the adjustability of the looper 48. Directly adjacent the bearing lug 113 a pivotable frame 117 is mounted upon the shaft 104 in the cheeks 118 and 119. A toothed gear 120 is received between these cheeks and is secured to the shaft 104 by means of a screw 121. A toothed gear 123 mounted by means of a screw 122 upon the shaft 55 of the feeder wheel 57 meshes with toothed gear 120 and is likewise received between the cheeks 118 and 119 of the pivotable frame 117,

The free end of the pivotable frame 117 (Figs. 2 and 4) is secured to the base plate 1 by means of an adjusting screw 124 which engages a threaded bore 125 in a boss 126. A pressure spring 127 is disposed around the adjusting screw 124 which, on the one end rests against the boss 126, and on the other end in a bore 128 of the frame 117. Rotating the screw 124 provides for vertical adjustment of the pivotable frame with the shaft 55 journalled therein and thus also for vertical adjustment of the feeding wheel 57.

The shifting bar 108 (Fig. 5) of the draw key 106 of the shiftable transmission 95 is guided in hollow shafts 104 and 60 and journalled for rotation and longitudinal movement in a threaded' plug 129 in hollow shaft 60. The free end of the shifting bar 108 (see Fig. 2) is provided with a threaded portion 130 upon which is mounted a disk 132 provided with opposite engagement surfaces 131 and is secured by means of a lock nut 133. The disk 132 is provided with an annular groove 134 which receives two oppositely disposed studs 136 defined by screws 135 which are in threaded engagement with a bifurcated end 137 of a transfer lever or pitman 138. The latter extends through an aperture 139 in the base plate 1 and is journalled on a collar stud 140 (Figs. 6 and 7) secured at its reduced end 141 in a bore 142 of a member 143 in the standard 2 by means of a screw 144. The other end of the lever 138 is also bifurcated and engages by means of fork 145 a collar screw 146 which is in threaded engagement with a disk 147 secured to one end of a hollow shaft 148. This shaft is rotatably mounted in a bore 149 of a cast extension member 150 at the front end of the standard 2 and supports at the other end which extends from the member 150 a shifting lever 151 which is secured in position by means of a set screw 152. An indicator scale 153 which partly encompasses the extension 150 is provided on shifting lever 151.

The shifting bar 83 (Figs. 5 and 2) of the draw key 81 in transmission 68 is guided through hollow shaft 77 and journalled in a threaded plug 154 for longitudinal movement. The end of the shifting bar 83 which extends from the shaft 77 is provided with a threaded portion 155 to which is threaded a disk 156, in the same manner as the disk 132 of the shifting bar 108, and is secured by means of a lock nut 157.

Two studs (Fig. 6) defined by screws 159 extend in opposite directions into an annular groove 158 of disk 156 and are threaded into a bifurcated end 161 of a connecting lever 162. This lever extends through the aperture in the base plate 1 in a manner similar to the transfer lever 138 and is likewise journalled upon the collar bolt 140.

Both transfer levers 138 and 162 are held by a head 163 of the collar stud 140. The other end 164 of the lever 162 is likewise bifurcated and engages a collar screw 165 which is in threaded engagement with a lever 167 secured to a shifting shaft 166. The shaft 166 is rotatably mounted in the hollow shaft 148 and provided with a shifting lever 168 at its free end which extends from the standard 2 to which it is fastened by means of a set screw 169.

A ring 170 is formed on the shifting bar or lever 168 and rests against the shifting lever 151. A cover 171 is mounted in a recess 172 of the extension 150 and partly encloses the shifting lever 151 and its indicator scale 153 (see Fig. 8). As the bottom side the cover 171 is provided with a recess 173 for the shifting lever 151, and its front part 174 which extends between levers 151 and 168 is provided with an aperture forming a surface 175 for the ring 170 of the shifting lever 168.

At the inner and outer surfaces of front part 174 of the cover 171 a plurality of grooves 176 and 177 are provided corresponding to the number of shifting positions of the two shifting levers 151 and 168 for engagement by pressure members 178 and 179 which are received in bores 180 and 181 of the shifting levers 168 and 151 and which are under the biasing effect of springs 182 and 183.

On the top side of the cover 171 a window 184 (Fig. 8) is provided through which can be seen a part of the graduations on the scale 153 of the shifting lever 151. Furthermore, a scale 185 is provided on the top side of the housing 171 which cooperates with a scored mark 186 provided on the shifting lever 168.

The Arabic numerals provided in groups of four on scale 185 indicate the chosen stitch lengths, and the Roman numerals of the scale 153 indicate the stitch groups associated with the Arabic numerals.

The setting of the desired stitch length is effected as follows:

If it is desired, for example, to set up for a stitch length 3.2 mm., the shifting lever 168 is set to the groups of fours which includes stitch length 3.2 mm., and the shifting lever 151 is moved in such a manner that the Roman IV can be seen through the window 184 of the cover 171 (Fig. 8). By operating the shifting levers 151 and 168 the transfer levers 138 and 162 cause the draw keys 106 and 81 mounted within shifting keys 108 and 83 to engage the corresponding toothed gears of the shifting transmissions 95 and 68.

Having now described my invention with reference to the operative embodiment thereof illustrated in the drawings, I do not wish to be limited thereto, but what I desire to protect by letters patent of the United States is set forth in the appended claims.

I claim:

l. Feeding mechanism for sewing machines of the type having a base plate, a standard, a feeding wheel mounted on a wheel shaft in a vertically adjustable frame supported adjacent one end of and below said base plate, a gear on said wheel shaft, a pair of transmissions disposed end to end below said base plate, each comprising two sets of gears axially aligned on parallel hollow shafts with one set of gears of one said transmission in axial alignment with one set of gears of the other of said transmissions, a shaft connected to one of said hollow shafts pivotally supporting said frame and a drive gear meshing with said wheel gear, a first and a second shifting bar each having a spring biased draw key at one end each extending into one of said parallel shafts, one key for engagement with the gears of one said transmission and the other for engagement with the gears of the other said transmission, the other ends of said draw bars extending from said hollow shafts proximate the other end of said base plate below said standard, setting means including first and second concentric setting members mounted externally of said standard and connecting gear extending respectively between said first and second draw bar and said first and second member, said members being operative to move said keys associated with said first and second bars into engagement with selected gears of said transmission as indicated on said setting means.

2. Feeding mechanism for sewing machines of the type having a base plate, a standard, a feeding wheel mounted on a wheel shaft in a vertically adjustable frame supported adjacent one end of and below said base plate, a gear on said wheel shaft, a pair of transmissions disposed end to end below said base plate, each comprising two sets of gears axially aligned on parallel hollow shafts with one set of gears of one said transmission in axial alignment with one set of gears of the other of said transmissions, a shaft connected to o-ne of said hollow shafts pivotally supporting said frame and a drive gear meshing with said wheel gear, a first and a second shifting bar each having a spring biased draw key at one end each extending into one of saidA parallel shafts, one key for engagement with the gears of one said transmission and the other for engagement with the gears of the other said transmission, the other ends of said draw bars extending from said hollow shafts proximate the other end of said base plate below said standard, setting means including first and second concentric setting members mounted externally of said standardv and connecting gear kwith one set of extending respectively between said first and second draw bar and said first and second member, said members being operative to move said keys associated'with said first and second bars into engagement with selected gears of said transmission as indicated on said setting means, and a housing mounted below the base plate of said machine encasing said transmissions.

3. Feeding mechanism for sewing machines of the type having a base plate, a standard, a feeding wheel mounted on a wheel shaft in a vertically adjustable frame supported adjacent one end of and below said base plate, a gear on said wheel shaft, a pair of transmissions disposed end to end below said base plate, each comprising two sets of gears axially aligned on parallel hollow shafts gears of one said transmission in axial aiignment with one set of gears of the other of said transmissions, a shaft connected to one of said hollow shafts pivotally supporting said frame and a drive gear meshing with said wheel gear, a first and a second shifting bar each having a spring biased draw key at one end each extending into one of said parallel shafts, one key for engagement with the gears of one said transmission and the other for engagement with the gears of the other said transmission, the other ends of said draw bars extending from said hollow shafts proximate the other end of said base plate below said standard, setting means including first and vsecond concentric setting members mounted externally of said standard and connecting gear extending respectively between said first and second draw bar and said first and second member, said members being operative to move said keys associated with said first 'and second bars into engagement with selected gears of said transmission as indicated on said setting means, said standard having a boss and said concentric setting members being mounted on said boss in concentric relationship thereto.

4. Feeding mechanism for sewing machines of the type having a base plate, a standard, a feeding wheel mounted on a wheel shaft in a vertically adjustable frame supported adjacent one end of and below said base plate, a gear on said wheel shaft, a pair of transmissions disposed end to end below said base plate, each comprising two sets of gears axially aligned on parallel hollow shafts with one set of gears of one said transmission in axial alignment with one set of gears of the other of said transmissions, a shaft connected to one of said hollow shafts pivo-tally supporting said frame and a drive gear meshing with said wheel gear, a first and a second shifting bar each having a spring biased draw key at one end-each extending into one of said parallel shafts, one key for engagement with the gears of one said transmission and the other for engagement with the gears of the other said transmission, the other ends of said draw bars extending from said hollow shafts proximate the other end of said base plate below said standard, setting means including first and second concentric setting members mounted externally of said standard and connecting gear extending respectively between said first and second draw bar and said first and second member, said members being operative to move said keys associated with said first :and second bars into engagement with selected gears of said transmission as indicated on said setting means, said standard having a boss and said concentric setting members being mounted on said boss in concentric relationship thereto, and said boss being provided with an indicator scale for the second of said setting members and said first member being provided with an indicator scale cooperating with the indicator scale on said boss and having indicator markings for said second setting member.

5. Feeding mechanism for sewing machines of the type having a base plate, a standard, a feeding wheel mounted on a wheel shaft in a vertically adjustable frame supported adjacent one end of and below said base plate, a gear on said wheel shaft, a pair of transmissions disposed end to end below said base plate, each comprising two sets of gears axially aligned on parallel hollow shafts with one set of' gears ofone' said transmission in axial alignment `with one set of gears of the otherV of' said transmissions, a

shaft connected to one'ofl said hollow shafts pivotallyy supporting said frame and adrive gear meshing with said wheel gear, a first and a second shifting bareach having a spring biased draw key atone end each extending into one of said parallel shafts, one key-for engagementl with the gears of one said transmission and the otherV for engagement with the gears of the other saidv transmission, the other ends of said draw bars extending from said hollow shafts proximate the other end of said base plate below said standard, setting means including first and second concentric setting members mounted externally of said standard and connecting gear extending respectively between said first and second drawbar and said first 1 and second member, said members being operative to move said keys associated-with said first and second bars into engagement with selected gears of said transmis- 8 sion as" indicated-'on said setting means, 'saidstandard havingajboss and said concentric-setting members being mounted'on said boss in concentric relationship thereto, and-said boss being provided with anindicator scale for the second of Vsaid setting members and said first member being provided with an Vindicator scale cooperating with the indicator scale on said boss and having indicator markings for said second setting member, a cover being disposed aroundi saidv indicator scales having a window ex'- posing portions of said scales.

References Cited in the ile of this patent UNITED STATES PATENTS 641,219 McClellan Ian. 9, 1900 795,222 Hanson July 18, 1905 1,864,136 Knox June 21, 1932 2,254,779 Myers Sept. 2, 1941 

